optimise list.extend()

Cython/Compiler/Builtin.py

@@ -287,6 +287,8 @@ builtin_types_table = [
                                     BuiltinMethod("reverse", "T",    "r", "PyList_Reverse"),
                                     BuiltinMethod("append",  "TO",   "r", "__Pyx_PyList_Append",
                                                   utility_code=UtilityCode.load("ListAppend", "Optimize.c")),
+                                    BuiltinMethod("extend",  "TO",   "r", "__Pyx_PyList_Extend",
+                                                  utility_code=UtilityCode.load("ListExtend", "Optimize.c")),
                                     ]),
 
     ("dict",    "PyDict_Type",     [BuiltinMethod("__contains__",  "TO",   "b", "PyDict_Contains"),

Cython/Utility/Optimize.c

@@ -52,6 +52,20 @@ static CYTHON_INLINE int __Pyx_ListComp_Append(PyObject* list, PyObject* x) {
 #define __Pyx_ListComp_Append(L,x) PyList_Append(L,x)
 #endif
 
+//////////////////// ListExtend.proto ////////////////////
+
+static CYTHON_INLINE int __Pyx_PyList_Extend(PyObject* L, PyObject* v) {
+#if CYTHON_COMPILING_IN_CPYTHON
+    PyObject* none = _PyList_Extend((PyListObject*)L, v);
+    if (unlikely(!none))
+        return -1;
+    Py_DECREF(none);
+    return 0;
+#else
+    return PyList_SetSlice(L, PY_SSIZE_T_MAX, PY_SSIZE_T_MAX, v);
+#endif
+}
+
 /////////////// pop.proto ///////////////
 
 static CYTHON_INLINE PyObject* __Pyx_PyObject_Pop(PyObject* L); /*proto*/

tests/run/list.pyx

@@ -104,10 +104,43 @@ def test_list_pop_all():
     """
     cdef list l1
     l1 = [1,2]
+    i = 0
     try:
         l1.pop()
+        i = 1
         l1.pop(-1)
+        i = 2
         l1.pop(0)
+        i = 3
     except IndexError:
-        return True
+        return i == 2
     return False
+
+def test_list_extend():
+    """
+    >>> test_list_extend()
+    [1, 2, 3, 4, 5, 6]
+    """
+    cdef list l = [1,2,3]
+    l.extend([])
+    l.extend(())
+    l.extend(set())
+    assert l == [1,2,3]
+    assert len(l) == 3
+    l.extend([4,5,6])
+    return l
+
+def test_none_list_extend(list l):
+    """
+    >>> test_none_list_extend([])
+    [1, 2, 3]
+    >>> test_none_list_extend([0, 0, 0])
+    [0, 0, 0, 1, 2, 3]
+    >>> test_none_list_extend(None)
+    123
+    """
+    try:
+        l.extend([1,2,3])
+    except AttributeError:
+        return 123
+    return l